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Air-tightness, draugths and energy consumption

Draughts from floor, doors, windows, etc. and problems in achieving a comfortable room temperature can result from inadequate or defective air-tightness in a building. The Danish Technological Institute has in many cases helped designers, builders and residents to detect air leaks so that these can be repaired.

As buildings become increasingly better insulated, heat loss through air leaks and thermal bridges are contributing to an ever greater proportion of the total energy consumption. At the same time air leaks and thermal bridges can in some cases result in producing critical levels of moisture condensation in a building.

A blower-door test can identify unsealed cracks and openings which can give rise to draughts and therefore increased energy consumption. With a pressure change of for example 50 Pa, and using a smoke pencil it is possible to detect air leaks and visually assess their size.

It is also possible to detect air leaks using thermography, although this requires a difference between inside and outside air temperatures of around 10 degrees C. Independent of an air-tightness test, a thermographic test can also reveal any thermal bridges in the building envelope.

Air-tightness tests and thermography are often carried out simultaneously, thereby providing a complete picture of a building envelope’s condition without destructive intervention.